1. Field of the Invention
This invention generally relates to the field of communications systems providing acknowledge back response capability for portable communication receivers, and more specifically to a system and method for optimally transmitting the acknowledge back responses received from the portable communication receiver at a remote receiving stations to a central receiving station.
2. Description of the Prior Art
Communication systems providing acknowledge back response capability have been available for a number of years. One such system enables a portable communication receiver having acknowledge back capability, to immediately communicate back a response, after the receiver has been initially contacted. The response provided may be a voice, numeric or alphanumeric message informing the originator of the communication that the message was successfully received by the portable receiving unit, and may further provide a response to the received message. Such acknowledge back systems have generally been only suitable for use in small, on-site systems, having a single central transmitter, and one or more wire-line connected acknowledge back system receivers for receiving the acknowledge back responses. The number of acknowledge back system receivers provided was a function of the acknowledge back transmitter power output provided with the portable communication receiver. Such transmitter power outputs were generally low, much less than one watt, due to the requirement for portability of the communication receiver, and the necessity to minimize the size of the battery subsequently required.
For large, wide area systems, the infrastructure required for providing acknowledge back response capability becomes considerably more complex. Wide area systems require messages intended for the portable communication receivers to be inputted through a terminal, such as a paging terminal, located at a central location. The messages are then distributed via wire-line or via link transmitters and receivers to each of a number of remote system transmitters or remote stations. The messages are then transmitted from the central station and from all remote system transmitters in a simulcast manner. In such systems, the number of communication receivers which can be in operation is high, ranging from one to ten thousand units and more, and the requirement for message throughput to support such a large number of communication receivers is equally high. The provision of acknowledge back capability in such a system places a tremendous strain on the ability of the system to maintain the message throughput. The problem may be further complicated by an increase in the number of system receivers which are required to support the communication receiver acknowledge back responses, and the problem of providing an efficient distribution of these responses from each of the remote stations back to the central station so that the response may be delivered to the message originators. An acknowledge back system for handling acknowledge back responses in an wide area communication system is required which does not compromise message throughput. The acknowledge back system must also insure reliable transmission of the communication acknowledge back responses received at the remote stations back to the central station for ultimate distribution back to the message originators.